It's a NVidia GeForce 9600 GT on XP. It's really strange as Firefox appears to start to try and render a web page then hangs. One would think it's trying to use that driver for the web page hardware rendering.

Only the broswer windows close, minimise and max/restore works. Though once, I either disable or uninstall the "mv video hook driver 2" v1.22, the browser works fine again.

I thought about installing an older version of the video driver but the performance of UltraVNC has been good enough with the hook driver disabled, so I thought I would just let you know instead in case there is a bug that affects others as well.

For instance, multi-monitor support. I think that is only possible with the mirror driver.Not to mention it should require less resources to use the mirror driver.

With "Windows 7" 64Bit I actually only get decent response times when using the mirror driver.On 32Bit Vista it is also way better with the mirror driver. There isn't much difference on a XP system though but it might make a difference if the system is older (and therefore slower).

I ran into a similar issue.Interestingly so far only on a XP system (with an ATi integrated HD 4250). (It works fine on Vista 32Bit and Windows 7 64Bit but both have different graphic cards as well, so...)Firefox itself doesn't really "hang" but on the UltraVNC viewer I only see a black screen (well not always, sometimes I see parts of it displayed correctly). On the PC itself everything is displayed correctly.I think this might be related to the "hardware acceleration" option of "Firefox 4" (haven't tried to disable that option yet).

I have now done further checks and it seems to definitely be related to the "hardware acceleration".Without it, it seems to work fine.

Furthermore, I now experienced it pretty equivalent to what was written here, for a few seconds it seemed to work (with active hardware acceleration) but then Firefox isn't getting refreshed anymore (but that doesn't mean it hangs because it still works (e.g. I was able to press OK and such things, I just didn't see the changes over the viewer).

If it can't be fixed directly in the driver - though I hope there will be a solution directly there - maybe for such "windows" UltraVNC should "fall back" to Poll Window and Hook DLL, ...

The problem is made worse when you are trying to create a reliable method to reproduce the problem in that it eventually mucks up the UltraVNC server so that it loses it connections and will not reconnect until the process is restarted.